Losing fat is good for your heart, but maintaining muscle and bone is crucial for staying mobile and living independently, said Kristen Beavers, a health and exercise science professor at Wake Forest University.

"Everybody says that they want to lose weight, but what they really mean is that they want to lose fat," she said. "And, for older adults in particular, maintaining muscle is a vital part of any plan to lose weight."

To do that, she suggests resistance training -- what used to be called "weight training." In a study published recently in the journal Obesity, Beavers showed that resistance training was more effective than walking at helping obese seniors lose weight and preserve muscle mass.

It's also important to be realistic when planning a weight loss/exercise program so you don't get discouraged and give up by early February, Beavers said. She suggested consulting with a fitness expert at a community facility, like the YMCA or a senior center. Both offer free or reduced rates for seniors.

"Maintaining lost weight is just as important as the initial weight loss, especially since older adults are more likely to regain fat mass than muscle or bone," she added.